United's home form has provided a backbone to their campaign-they have won 41 points at Old Trafford compared to 30 points away from home-and they have conceded a Premier League-low seven goals on their own soil.
This result leaves City 16 points clear of their local rivals with only five games remaining, making it mathematically impossible for United to catch them.
But a first Premier League title, to go with the three La Liga titles he won as manager of Barcelona and the three Bundesliga titles he delivered for Bayern Munich, will be particularly satisfying. They are now 20th in the Premier League, 12 points behind Swansea City who are 17th. West Brom were content to let United try - and fail - to thread precise passes through tiny gaps. In sealing the league at this stage, City matched the record for the earliest title win - held by United since 2001.
United's comeback at the Etihad from a 2-0 half-time deficit offered their supporters a rare fillip of flair and excitement after a hard season where their style of play has hardly endeared Jose Mourinho to the club's fanbase.
Although, observers know that it was a matter of time before City is crown the champion of the lead.
"Unbelievable season for us", said midfielder Kevin De Bruyne, perhaps City's standout player over the past eight months.
Speaking after the win over Tottenham, Guardiola admitted winning the title in England would be one of the greatest achievements of his glittering career. "Very happy to call us champions this year".
"Before the derby [lost 3-1 against Manchester United] it was in our hands", Guardiola said after the game at Wembley.
City were without Aguero, who had sustained a rib injury in a vehicle crash, but Kevin De Bruyne made sure the Argentina striker wasn't missed as he slammed in the victor in the 67th minute. They were unbeaten in the Premier League until January 14, when Liverpool ended that awesome run at Anfield.
The Baggies are as good as down following a shocking season and all that is left to play for is pride.